Process for the mercerization of cotton fabrics with liquid ammonia and ammonia/amine solutions

ABSTRACT

Woven and knit cotton fabrics with improved strength, smooth drying appearance, dimensional stability, abrasion resistance, and hand have been produced by rapid and continuous tension mercerization with liquid ammonia using an improved chainless mercerizer.

nite States Patent Ca1arnari, Jr. et al.

[ PROCESS FOR THE MERCERIZATION OF COTTON FABRICS WITH LIQUID AMMONIA AND AMMONIA/AMINE SOLUTIONS [75] Inventors: Timothy A. Calamari, Jr.; Wilson A. Reeves; Sidney P. Schreiber; Albert S. Cooper, Jr., all of Metairie, La.

[73] Assignee: The United States of America as represented by the Secretary of Agriculture, Washington, DC.

[22] Filed: May 7, 1971 [21] Appl. No.: 141,359

[52] US. Cl 8/115.7, 8/18, 8/31, 8/34, 8/1 16.4, 8/125, 8/181, 8/184,

[51] lnt. Cl. D06m 1/06, D06m 1/10 [58] Field of Search 8/1l5.7, 116.2, 125, 116.3

[56] References Cited UNITED STATES PATENTS 3,406,006 10/1968 Lindberg et a1. 8/125 [451 Nov. 19, 197

3,449,060 6/1969 Schenck 8/125 3,549,310 12/1970 3,560,140 2/1971 3,724,243 4/1973 Calamari et a1 8/125 UX OTHER PUBLICATIONS Gogek et al., Textile Research Journal, Vol. 39, pp. 543-547, (1969).

Primary Examiner-George F. Lesmes Assistant Examiner-J. Cannon Attorney, Agent, or Firm-M. Howard Silverstein; Max D. Hensley 5 7 ABSTRACT 8 Claims, No Drawings PROCESS FOR THE MERCERIZATION OF COTTON FABRICS WITH LIQUID AMMONIA AND AMMONIA/AMINE SOLUTIONS A non-exclusive, irrevocable, royalty-free license in the invention herein described, throughout the world for all purposes of the United States Government, with the power to grant sublicenses for such purposes, is hereby granted to the Government of the United States of America.

This invention relates to a process for the liquid am"- monia treatment of all-cotton and cotton/synthetic woven and knitted fabric. More specifically, it deals with a rapid process for the continuous tension mercerization of woven and knit fabric made of cotton and cotton/synthetic fibers with liquid ammonia which imparts improved wet wrinkle recovery, increased breaking and tearing strength, equal or better elongation at the break, improved smooth drying appearance after laundering, improved abrasion resistance, better hand, and increased ratio of wet to dry wrinkle recovery, without increasing dye substantivity.

In copending application Ser. No. 141,353, filed of even date, now Pat. No. 3,724,243, a device is disclosed which has utility in the treatment of yarn and fabrics with liquid ammonia. This application describes the apparatus used in the instant invention and has as its object the incorporation of graduated driven rollers of increasing diameter into a device of the prior art such that each driven roller becomes incrementally larger than the previous one in the direction of fabric travel.

ln copending application Ser. No. 141,360, filed of even date, now Pat. No. 3,767,359, a process is disclosed for the treatment of yarns composed of either cotton or cotton and synthetic fibers with liquid ammoma.

Heretofore it was known that immersion of cotton in liquid ammonia can bring about changes in fiber properties. These changes include enhanced moisture regain, increased fiber breaking strength, increased diameter of the fiber cross section, and in some cases modified crystalline form.

When native cellulose (Cellulose l) in cotton is treated with liquid ammonia, an unstable adduct is formed. Depending on the manner in which the ammonia is removed, either Cellulose l or Cellulose Il may result. 1f the ammonia is removed by water quenching ofthe complex, Cellulose l is regenerated. 1f the ammonia is removed by induced evaporation of the ammonia, Cellulose Ill primarily is formed. Evaporation results in a less ordered crystalline lattice than that obtained with water quenching, consequently the moisture regain and the reactivity of ammonia treated samples in which the ammonia was removed through evaporation is higher than those of samples which were water quenched.

It is also known that woven or knitted fabrics which contain natural cellulosic fibers are modified by liquid ammonia, so that they exhibit enhanced dimensional stability, increased strength, nonironing properties, shrink resistance, and dyeing properties about equivalent to caustic mercerized cotton.

When a relaxed cotton fabric is treated with liquid ammonia and allowed to remain relaxed until the ammonia is essentially removed, the product has high elongation, some improvement in strength, and increased dye affinity, but exhibits poor dimensional stability. When a relaxed cotton fabric is treated with liquid ammonia then stretched immediately after immersion during removal of the ammonia, the product has substantially improved strength, good dimensional stability, and increased dye affinity, but exhibits reduced elongation at break.

lnorder to effect many of these changes in fabric properties, in accordance with the prior art it is necessary to immerse the fabric in liquid ammonia for at least 15 seconds to allow the fibers to swell greatly before the ammonia is removed. This makes such a process too slow for efficient and rapid commercial production.

We have now found that improvement in wrinkle recovery, tear strength, and abrasion resistance of liquid ammonia treated fabrics are due largely to changes in the surface of the fibers, while changes in crystalline structure, dyeing properties, and extensibility are due largely to internal changes of the fiber. In the present invention a very rapid process has been discovered for the treatment of fabrics with liquid ammonia to bring about some substantial changes in the fabric through modification of the surface of the fiber as well as some internal changes. These changes are very useful in the production of improved consumer products. In our process, fabric is held under tension in both warp and fill (or course and wale) directions while it is rapidly passed through a bath of liquid ammonia, and subsequently until the ammonia is essentially removed. Furthermore, we have discovered that when cotton containing fabrics are tensioned sufficient to elongate the fabric before, during and after immersion in liquid ammonia, and until the ammonia is essentially removed, the fabric exhibits increased strength, dimensional stability, unchanged dyeing properties, enhanced luster, and slightly reduced elongation at break.

ln our process fabric is passed over one or more cylinders (or rolls) then through liquid ammonia and subsequently over a series of cylinders wherein the fabric is completely in contact with the cylinders from the point where the fabric emerges from the liquid ammonia bath to the point where about percent of the ammonia is removed. The cylinders are sized and arranged so that the fabric is progressively stretched as it proceeds from the area of the ammonia bath to the point where 90 percent of the ammonia is removed from the fabric either by evaporation or water quenching. The fabric is stretched a total of about from 1 to 15 percent depending on the fabric construction. The amount of tension applied to a fabric during the process is sufficient to elongate the warp or wale about from 1 to 15 percent and sufficient to restrict shrinkage in the fill or course direction to less than 5 percent. The amount of restriction put on filling shrinkage is directly related to the tension applied in the warp, and the friction developed between the fabric and the cylinders over which the fabric passes during the processing. The immersion time in the liquid ammonia is about from 0.1 sec. to about 1.0 sec. At least 90 percent of the ammonia is removed within l2 sec. after the initial immersion. When processed under these conditions, the fibers are not permitted to swell to the maximum but are mercerized. Because of the lack of sufficient internal changes in the fibers caused by the manner of processing the treated cotton exhibits essentially unchanged dyeing properties.

The liquid ammonia suitable for use in this process may contain a solute such as methylamine, ethylamine, propylamine, ammonium thiocyanate, sodium thiocyanate, calcium thiocyanate, quarternary ammonium hydroxides, ammonium acetate, ammonium nitrate, ammonium iodide, ammonium bromide, urea, and a combination of these solutes. The amount of solute that can suitably be contained in the liquid ammonia varies according to the end results to be produced in the treated fabric. Where appropriate, the solute may constitute about one-half the weight of the solution.

Fabrics treated in accordance with this process are particularly well suited to use in durable press applications. When treated with cellulosic crosslinking agents using commercial pad, dry, and cure techniques the ammonia pretreated samples exhibited improved washwear ratings, improved abrasion resistance, improved dry wrinkle recovery, improved tear, a softer hand, and better dimensional stability than similar fabrics not given the ammonia pretreatment. Fabrics suitable for use in this invention should contain about 25 percent or more cotton. The remainder of the fabric can be made up of various synthetic fibers, such as polyester, polyamides, acrylics, rayon, etc. Cellulosic crosslinking agents are conventional textile finishing agents which include N-methylol amides, pseudo amides, formaldehyde, and related materials which react with cotton in the presence of an acid catalyst.

The following examples will further illustrate the embodiment of our invention.

EXAMPLE 1 This example illustrates the continuous tension mercerization of sheeting fabrics made of all-cotton and of a 50/50 blend of cotton and polyester fibers with liquid ammonia using an improved chainless mercerizer which permitted fabric to be mercerized under a constantly increasing tension. In this example, mercerization was terminated by quenching the ammonia treated fabr c wit otwate The all-cotton sheeting sample had a thread count of 120 X 70. The blended sheeting had 50 percent cotton and 50 percent polyester in both the warp and filling directions and a thread count of 120 X 70. Eight-inch widths of each fabric were batched on feed rolls. The batched rolls were then placed on a feed assembly which permitted the adjustment of back tension. The fabric was then run through the improved chainless mercerizer. Liquid ammonia was applied to the fabric by means of a treatment tray located under one of the lower cylinders (rolls) of the mercerizer. Immersion time was about 0.5 sec. Mercerigation was allowed to one graduated driven roller to the next. The dimensions of both the all-cotton and the cotton/polyester blended sheeting both before and after mercerization are given in Table 1.

After removal of the fabrics from the mercerizer, they were crosslinked with a solution containing 10 percent dimethylolmethoxyethyl carbamate and 0.8 percent Zn( NO -6H O using a conventional pad, dry, cure procedure. In Table 2 the physical properties of the all-cotton samples before and after crosslinking are compared. Those for the blended cotton/polyester samples are given in Table 3.

EXAMPLE 2 This example is identical to Example 1 except that the ammonia was removed from the fabric through evaporation induced by means of two 150 watt infrared lamps. Evaporation was begun 3 see. after the fabric was immersed in the liquid ammonia, and was over percent complete 10 sec. Some physical properties of the all-cotton and blended samples before and after mercerization and crosslinking are compared in Tables 4 and 5.

Parts of each fabric, before application of the crosslinking treatment, were dyed with several dyes of various classes; i.e., Solantine Blue 4GL (a direct dye). Brilliant Green BNWP (a vat dye) and Procion Red M-GS (a reactive dye) using conventional procedures. In all cases those samples dyed after being processed in accordance with this invention were no deeper in shade than the non pretreated controls.

EXAMPLE 3 This example illustrates the continuous tension mercerization of a sample of cotton tubular knit fabric with liquid ammonia. The fabric used was a plain jersey knit from a greige 40/2 balanced yarn. It had 41 courses and 34 wales per inch and weighed 3.0 oz./yd The flattened width of the tube was about 5 in. A floating spreader bar was placed inside the tube so that it spread the knit jersey immediately before entering the first nip of the mercerizer. Ammonia was applied as indicated in Example 1, and removed using infrared lamps as in Example 2. Over 90 percent of the ammonia was removed within 12 see. after the initial immersion in ammonia. After mercerization, several samples were crosslinked with dimethylolmethoxyethyl carbamate for enhanced dimensional stability to washing. The Mullen bursting strength data for these samples are given in Table 6.

As the data show the bursting strength of ammonia mercerized fabrics before and after the crosslinking treatment are greatly improved over those of nonpree esisieeiinlsed telifa TABLE 1 DIMENSIONAL CHANGES IN NH, MERCERIZED SHEETING DIMENSIONS (IN-l Before After NH, 'lrcutmcnt NH'lTrggtmcnt Chung;

Warp Filling Wurp Filling Wurp Filling Areu Cotton sheeting 52.0 7.9 55.0 7.8 +5.8 -l .3 +4.4 Cotton/polyester sheeting 52.0 8.0 54.2 7.9 +4.2 -l .3 +2.9

proceed for 8 see. from the initial immersion in ammo nia. Hot water was then applied to the ammonia treated fabric to terminate the mercerization process abruptly.

Th abr v wa tia hed P 9$Ii lP "R i e m] As can be seen from this data, filling shrinkage during ammonia mercerization was held to a minimum. Elongation of the warp resulted in an overall increase in fabric area.

TABLE 2 SOME PROPERTIES OF LIQUID AMMONIA TREATED COTTON WHEN THE AMMONIA IS REMOVED BY WATER QUENCHING Tearing Strength Stoll Flex Abrasion Wrinkle Recovery Angle (w+f) Filling (gms.) Cycles (warpt) (Conditioned) (Wet) Control (120 X 70 cotton sheeting) 907 7 I016 209 176 Crosslinked control 327 I59 271 259 Liquid NH treated 913 2038 I85 218 Liquid NH; treated then crosslinked 360 t 216 278 260 irosslinked with 10% DMMEC and 8'1 Zn(NO ),'6H,O using a conventional pad dry, and cure treatment as used in the production of wash wear and durable press a ncs.

1 Eight seconds from initial immersion until water quenched TABLE 3 SOME PROPERTIES OF LIQUID AMMONIA TREATED BLENDED FABRIC WHEN THE AMMONIA IS REMOVED BY WATER QUENCHING Tearing Strength Stoll Flex Abrasion Wrinkle Recovery Angle (w+f) Filling (gms.) Cycles (warp) (Conditioned) (Wet) Control (120 X 70 blended sheeting) 1733 3814 260 267 Crosslinked control 733 2096 281 277 Liquid NH; treated l9l3 3058 248 273 Liquid NH treated then erosslinked 827 2098 290 281 Crosslinked'with 10' DMMEC and 8'1 Zn(NO,),-6H,O using a conventional pad. dryand cure treatment as used in the production of wash wear and durable press bricst Eight seconds from initial immersion until water quenched.

TABLE 4 SOME PROPERTIES OF LIQUID AMMONIA TREATED COTTON FABRIC WHEN THE AMMONIA IS REMOVED BY HEAT INDUCED EVAPORATION Tearing Strength Stoll Flex Abrasion Wrinkle Recovery Angle (w+f) Filling (gmsI) Cycles (Warp) (Conditioned) (Wet) Control (120 X 70 cotton sheeting) 907 I016 209 176 Crosslinkcd control 327 159 271 259 Liquid NH: treated 960 1796 219 210 Liquid NH; treated then crosslinked 527 330 282 252 Crosslinked with 10% DMMEC and 8'7r ZntNO:),-6H,O using a conventional pad, dry. and cure treatment as used in the production otwash wear and durable press fabrics. V

2 The ammonia was in the fabric a total of 10 seconds from initial immersion until at least 90% of the ammonia was removed using heat induced evaporation.

TABLE 5 SOME PROPERTIES OF LIQUID AMMONIA TREATED BLENDED FABRIC WHEN THE AMMONIA IS REMOVED BY HEAT INDUCED EVAPORATION Tearing Strength Stoll Flex Abrasion Wrinkle Recovery Angle (w+f) Filling (gms.) Cycles (warp) (Conditioned) (Wet) Control (120 X 70 blended sheeting) 1733 3814 260 267 (50% polyester/50% cotton) Crosslinked control 733 2096 281 277 Liquid NH, treated 1783 5196 272 280 Liquid NH treated then crosslinkcd' 947 4373 v 294 284 Crosslinked with It); DMMEC and 8% Zn(NO;),6H 0 using a conventional pad. dry, and cure treatment as used in the production of wash wear and durable press fabrics.

The ammonia was in the fabric a total of 10 seconds from initial immersion until at least 90% of the ammonia was removed using heat induced evaporation,

TABLE 6 We claim:

Mullen Bursting Strength (psi.)

sions, a fibrous fabric selected from the group consist- Z: ing ofa cotton fabric and a cotton/synthetic fiber blend Li uid ammonia treated as fabric containing at least 25 percent of cotton. immersthen crosslinked 64 Crosslinked with lllli dimethylolniethoxyelltyl carhamatc and 0,856

ZnlNOqlg'hHg) using conventional pad. production of wash'wear and durable press fabrics.

dry. and cure procedure as used in the 2 The ammonia was in fabric a total of 12 seconds from the initial immersion until at least 905i of the ammonia was removed using heat induced evaporatlon.

ing the tensioned fabric in liquid ammonia for a period of about from 0.1 second to 1.0 second, stretching the removing ammonia from the fabric by volatilization, continuing the tensioning and progressive stretching of -the fabric until at least about 90 percent of the ammonia has been removed from the fabric by volatilization, the time interval measured from immersion of the fabric in the liquid ammonia until at least about 90 percent of the ammonia has been removed by volatilization being limited to within 12 seconds and the dimensional stressing of the fabric accomplished by reason of the tensioning and progressive stretching of the fabric being maintained within the limits of about from 1 to 15 percent elongation relative to the length dimension and sufficient to restrict shrinkage in the width dimension to less than 5 percent, thereby to obtain a fibrous fabric in which essentially only the fiber surfaces have been modified.

2. The process of claim 1 wherein the fabric is cotton fabric.

3. The process of claim 1 wherein the fabric is a cotton/synthetic fiber blend fabric containing at least 25 percent of cotton.

4. A liquid ammonia mercerizing process consisting of tensioning, in both the width and the length dimensions. a fibrous fabric selected from the group consisting of a cotton fabric and a cotton/synthetic fiber blend fabric containing at least 25 percent of cotton, immersimmersed fabric to a progressively increasing degree of tension over a series of incrementally larger rollers during the immersion and during the subsequent step of removing ammonia from the fabric by quenching the fabric with water and removing the water from the fabric by volatilization, continuing the tensioning and progressive stretching of the fabric until the fabric is dry, the time interval measured from immersion of the fabric in the liquid ammonia until at least about percent of the ammonia has been removed by the treatment with water being limited to within 12 seconds and the dimensional stressing of the fabric accomplished by reason of the tensioning and progressive stretching of the fabric being maintained within the limits of about from 1 to 15 percent elongation relative to the length dimension and sufficient to restrict shrinkage in the width dimension to less than 5 percent, thereby to obtain a fibrous fabric in which essentially only the fiber surfaces have been modified.

5. The process of claim 4 wherein the fabric is cotton fabric.

6. The process of claim 4 wherein the fabric is a cotton/synthetic fiber blend fabric containing at least 25 percent of cotton.

7. The product produced by the process of claim 1.

8. The product produced by the process of claim 4. 

1. A LIQUID AMMONIA MERCERIZING PROCESS CONSISTING OF TENSIONING, IN BOTH THE WIDTH AND THE LENGTH DIMENSIONS, A FIBROUS FABRIC SELECTED FROM THE GROUP CONSISTING OF A COTTON FABRIC AND A COTTON/SYNTHETIC FIBER BLEND FABRIC CONTAINING AT LEAST 25 PERCENT OF COTTOM, IMMERSING THE TENSIONED FABRIC IN LIQUID AMMONIA FOR A PERIOD OF ABOUT FROM 0.1 SECOND TO 1.0 SECOND, STRETCHING THE IMMERSED FABRIC TO A PROGRESSIVELY INCREASING DEGREE OF TENSION OVER A SERIES OF INCREMENTALLY LARGER ROLLERS DURING THE IMMERSION AND DURING THE SUBSEQUENT STEP OF REMOVING AMMONIA FROM THE FABRIC BY VOLATILIZATION, CONTINUING THE TENSION AND PROGRESSIVE STRETCHING OF THE FABRIC UNTIL AT LEAST ABOUT 90 PERCENT OF THE AMMONIA HAS BEEN REMOVED FROM THE FABRIC BY VOLATILIZATION, THE TIME INTERVAL MEAUSURED FROM IMMERSION OF THE FABRIC IN THE LIQUID AMMONIA UNTIL AT LEAST ABOUT 90 PERCENT OF THE AMMONIA HAD BEEN REMOVED BY VOLATILIZATION BEING LIMITED TO WITHIN 12 SECONDS AND THE DIMENSIONAL STRESSING OF THE FARBIC ACCOMPLISHED BY REASON OF THE TENSIONING AND PROGRESSIVE STRETCHING OF THE FABRIC BEING MAINTAINED WITHIN THE LIMITS OF ABOUT FROM 1 TO 15 PERCENT RLONGATION RELATIVE TO THE LENGHT DIMENSION AND SUFFICIENT TO RESTRICT SHRINKAGE IN THE WIDTH DIMENSION TO LESS THAN 5 PERCENT, THEREBY O TO OBTAIN A FIBROUS FABRIC IN WHICH ESSENTIALLY ONLY THE FIBER SURFACES HAVE BEEN MODIFIED.
 2. The process of claim 1 wherein the fabric is cotton fabric.
 3. The process of claim 1 wherein the fabric is a cotton/synthetic fiber blend fabric containing at least 25 percent of cotton.
 4. A LIQUID AMMONIA MERCERIZING PROCESS CONSISTING OF TENSIONING, IN BOTH THE WIDTH AND THE LENGTH DIMENSIONS, A FIBROUS FABRIC SELECTED FROM THE GROUP CONSCONSISTING OF A COTTON FABRIC AND A COTTON/SYNTHETIC FIBER BLEND FABRIC CONTAINING AT LEAST 25 PERCENT OF COTTON, IMMERSING THE TENSIONED FABRIC IN LIQUID AMMONIA FOR A PERIOD OF ABOUT FROM 0.1 SECOND TO 1.0 SECOND, STRETCHING THE IMMERSED FABRIC TO A PROGRESSIVELY INCREASING DEGREE OF TENSION OVER A SERIES OF INCREMENTALLY LARGER ROLLERS DURING THE IMMERSION AND DURING THE SUBSEQUENT STEP OF REMOVING AMMONIA FROM THE FABRIC BY QUENCHING THE FABRIC WITH WATER AND REMOVING THE WATER FROM THE FABRIC BY VOLATILIZATION, CONTINUING THE TENSIONING AND PROGRESSIVE STRETCHING OF THE FABRIC UNTIL THE FABRIC IS DRY, THE TIME INTERVAL MEASURED FROM IMMERSION OF THE FABRIC IN THE LIQUID AMMONIA UNTIL AT LEAST ABOUT 90 PERCENT OF THE AMMONIA HAS BEEN REMOVED BY THE TREATMENT WITH WATER BEING LIMITED TO WITHIN 12 SECONDS AND THE DIMENSIONAL STRESSING OF THE FABRIC ACCOMPLISHED BY REASON OF THE TENSIONING AND PROGRESSIVE STRETCHING OF THE FABRIC BEING MAINTAINED WITHIN THE LIMITS OF ABOUT FROM 1 TO 15 PERCENT ELONGATION RELATIVE TO THE LENGHT DIMENSION AND SUFFICIENT TO RESTRICT SHRINKAGE IN THE WIDTH DIMENSION TO LESS THAN 5 PERCENT, THEREBY TO OBTAIN A FIBROUS FABRIC IN WHICH ESSENTIALLY ONLY THE FIBER SURFACES HAVE BEEN MODIFIED.
 5. The process of claim 4 wherein the fabric is cotton fabric.
 6. The process of claim 4 wherein the fabric is a cotton/synthetic fiber blend fabric containing at least 25 percent of cotton.
 7. The product produced by the process of claim
 1. 8. The product produced by the process of claim
 4. 